This invention relates to food, and more particularly to textured protein that is useful in formulating fabricated foods for human and animal consumption.
Protein deficiency is common throughout many parts of the world, with protein malnutrition being the most wide spread and serious malnutritional problem in the underdeveloped areas of the world. Rapidly increasing population of the world is further worsening the shortage of protein supply. It is, therefore, necessary to utilize the available protein supply in a manner that is most efficient. Meat is one of the most popular sources of diet protein, and the American population has developed taste for the texture, flavor and mouthfeel of meat products. However, present economic conditions have led to high cost for meat products necessitating the development of meat analogs that are less expensive. Furthermore, the presence of cholesterol and highly saturated fats in meat limit their intake by people with certain health problems such as atheroschlerosis. Another sector of world population does not consume meats due to religious or personal beliefs. Therefore, a need exists for the development of palatable, high quality protein foods from new and less expensive protein sources. There are many sources of protein available. Besides meat, other animal proteins are poultry, fish, eggs, milk and milk products. Soybeans, peanuts, cereals and other plant or vegetable proteins are the other major protein sources. However, many of these plant proteins lack the required palatability to make them suitable for use. Various methods of modification of these protein sources are being used to make them more palatable and therefore, more acceptable. Processes also have been developed to utilize animal and plant proteins in fabricating foods similar in appearance, texture, flavor and taste to the natural foods already accepted.
One such process is basically known as texturization of proteins. There are three basic methods for forming texturized proteins. There is a spinning process, an extrusion process, and a glass-puffing extrusion process. The spinning process involves extruding a protein dope or solution through a die into a coagulation bath to form fibers. The problem becomes obvious during the extrusion of the dope and the determination of a proper coagulation bath. In the extrusion process, high pressures and temperatures are used to form a plexilaminate. In this product the cells of the product are longer in the direction of the extrusion. The glass-puffing process is also a high pressure and high temperature process. The use of high pressure and high temperature requires sophisticated, expensive equipment, capital, and skills to handle. The high temperature and pressure also damages the protein thus processed. Furthermore, the protein processed in this fashion still retains some of its undesirable flavor and taste characteristics. For example, the taste of the protein has not been improved. The type of protein being processed may well not have the desired palatability. Thus, while there exist processes for forming suitable texturized proteins, many problems still remain to be solved in producing acceptable protein substitutes for meat.
In the prior art spun protein processes, there is an effluent disposal problem. This effluent results from the basic nature of prior art wet processes. In order to treat the raw protein the raw material is dissolved in an alkali medium. For example, soy protein isolate can be dissolved in sodium hydroxide solution to form a protein dope. This solution of protein is then extruded into an acid coagulation bath. This acid bath coagulates the protein, and the protein fibers are formed. The fibers thus formed are tender and disintegrate upon cooking unless hardened in a salt solution bath. The fibers carry part of the salt solution and must be washed in order to remove the undesirable taste of salts. The acid bath, the salt bath, and the wash water complicate the waste disposal problems of the manufacturing plant. The process can be highly simplified if hardening can be accomplished by a simple single-step procedure that does not leave any disposable residues.
Recent developments in protein texturization include the sheeting and film forming technologies. These technologies, however, require forming and partial drying of a particular product before that product can be shaped and texturized. In addition, the textured product loses its shape and identity upon cooking unless pretreated with denaturing agents such as acids and salts. The liquid residues left in the denaturing or fixing process are similar to those in the spinning process and aggravate the waste disposal problem.
Therefore, it is desirable to develop a process for protein texturization that is simple, inexpensive, with minimum waste disposal problems, and having no adverse effect on the nutrition and flavor of the protein being texturized.